JAKARTA, Sept 26 (Reuters) - Indonesia has increased its 2018 coal production target to around 507 million tonnes from a previous target of 485 million tonnes, the Energy Ministry said on Wednesday, a move that may add to downward pressure on prices for the fuel.

Indonesia is the world’s top exporter of thermal coal, and it had earlier proposed additional output of up to 100 million tonnes to help the rupiah, whose value has fallen nearly 10 percent against the U.S. dollar this year.

The government has issued additional output quotas of 21.9 million tonnes, split among 32 coal miners, Energy and Mineral Resources Spokesman Agung Pribadi said in a text message.

Pribadi declined to provide details on the companies that received the additional quotas.

All of the additional output could be exported, he said, adding that no further applications for increases to 2018 coal output quotas are being reviewed by the ministry.

The country’s miners, though, are being conservative about increasing output and may face difficulties due to heavy equipment shortages, said Indonesian Coal Mining Association Executive Director Hendra Sinadia.

“This will definitely impact prices,” Sinadia said, referring to prices for coal with an energy content of up to 5,000 kilocalories per kilogram.

The Newcastle weekly index, the Asian benchmark, has declined 6 percent since Aug. 1, and was at $113 a tonne as of Friday.

“From August to September (prices) declined a lot,” he said.

The Indonesia Coal Benchmark Price (HBA) was set at $104.81 in September, down from $107.83 a tonne in August, government data showed.

Indonesia’s coal consumption for power by PLN and independent power producers is expected to reach 88.5 million tonnes in 2018, below a 2018 target of 92 million tonnes, PLN coal contract manager Tri Joko told reporters.

But in 2019, PLN expects coal consumption to increase to 96 million tonnes, Joko said.

“There are several PLN and independent power station projects that will come up this year and in 2019,” he said, adding that PLN’s forecast for economic improvement in Indonesia will mean more coal is required.

Indonesia’s coal consumption for power was at 82.2 million tonnes in 2017. (Reporting by Wilda Asmarini and Bernadette Christina Munthe; Additional reporting by Gavin Maguire in SINGAPORE; Writing by Fergus Jensen; Editing by Christian Schmollinger and Tom Hogue)